Knife sharpener



1966 J. PLEASANTS 3,289,498

KNIFE SHARPENER Filed April 15, 1965 United States Patent 3,289,498 KNIFE SHARPENER Jack Pleasauts, Somerville, N.J., assignor to Nova Products, Inc, Union, N.J., a corporation of New Jersey Filed Apr. 15, 1965, Ser. No. 448,385 3 Claims. (Cl. 7637) This invention relates to a knife sharpener and is more particularly concerned with a portable knife sharpener which is adapted to adjust itself automatically to the particular edge being sharpened.

Portable knife sharpeners for use in the kitchen, the work-shop, or elsewhere are well known and many dif ferent forms have been proposed. In general, they involve one or more abrasive surfaces against which the edge to be sharpened is drawn. In these prior constructions, however, the type of edge which can be given to the knife is limited, or considerable experience or dexterity is required on the part of the user. In the case of sharpeners having opposed abrasive surfaces between which the knife is drawn, for instance, the surfaces are fixed in space and are strictly limited in the form of the edge which can be provided. Frequently, however, it is not desired to provide the same edge on very knife, and there is a need for a portable sharpener of the character indicated which can be adjusted to provide different edges as desired. There is particularly a need for a portable knife sharpener which will automatically accommodate itself to the particular edge being sharpened.

It is accordingly an object of the present invention to provide a portable knife sharpener which has self adjusting cutting surfaces effective to sharpen a variety of knife edges.

In accordance with the invention, there is provided a sharpener of the nature indicated which comprises a housing, a pair of metal-cutting discs disposed in coplanar tangential relationship in the housing, but movable laterally in their common plane out of tangential contact, and adjustable spring means acting upon one of the discs to urge it under variable pressure into tangential contact with the other disc.

The nature and features of the invention will be more fully understood from the following detailed description of an illustrative embodiment, taken with reference to the accompanying drawing, wherein,

FIG. 1 is a perspective view of a portable knife sharpener embodying features of the present invention;

FIG. 2 is an end elevational View of the knife sharpener shown in FIG. 1, as seen from the right-hand end of FIG. 1;

FIG. 3 is a top plan view of the right-hand portion of the embodiment illustrated in FIG. 1;

FIG. 4 is a longitudinal cross-sectional view, partly in elevation, of the knife sharpener illustrated in FIG. 1, as seen generally along the line 44 of FIG. 1, and

FIG. 5 is another longitudinal cross-sectional View, partly in elevation, of the sharpener shown in FIG. 1, as seen generally along the line 5-5 of FIG. 3.

Referring now to the drawing, the embodiment of the invention illustrated comprises a knife sharpener unit, designated generally by the reference numeral 10, supported in a holder 12. The sharpener unit 10, which is best seen in FIGS. 3-5, is formed from a housing consisting of a body portion 14 and a cover plate 16, secured to each other by means of screws. As seen in FIGS. 3 and 5, the body portion 14 is formed with a recess 20 having semi-circular end walls 22 and 24 in which are freely seated two discs 26 and 28 formed from a hard steel-cutting material, such as silicon carbide. As seen in FIG. 3, in the embodiment illustrated the recess 20 has a depth which is about /2 the thickness of the body portion 14, and the cover plate 16 has a thickness 3,289,498 Patented Dec. 6, 1966 ice which is about /2 the thickness of the body portion. While the invention is in no way limited to any particular dimensions, by way of illustration a typical embodiment as illustrated in the drawing has a cover plate 16 which has a thickness of A; in. and a body portion 14 which has a thickness of A in., with the recess 20 having a depth of A; in. The body portion and the cover plate can have any convenient peripheral shape, but they are conveniently of a substantially rectangular outline, as illustrated, and their corners, such as the lower corners 30 and 32, can be cut away. It is only necessary for these elements to be of sufiicient size to accommodate the discs 26 and 28, and the other working parts which will be described below, and to accommodate a handle or casing, such as the holder 12, or securing means to attach the unit 10 to a suitable support. Thus, as illustrated, the holder 12 is formed with a recess 34 which is dimensioned to receive the unit 10 with a friction fit. At the same time, the unit 10 is formed with two holes 36 through which screws (not shown) may be passed, if it is desired to fix the unit in the holder, or if it is desired to remove the unit from the holder and to secure it to some other support, such as a work-bench.

Returning again to the construction of the sharpener unit 10, the body portion 14 and the cover plate 16 are formed with aligned central substantially-triangular cutouts 38 and 40, respectively, through which the metalcutting discs 26 and 28 are visible and into which the knife blade to be sharpened is received, as seen in FIG. 1. When the cutouts extend below the top surface of the holder 12, as in the embodiment illustrated, the holder is also suitably notched, as shown at 42, to accommodate the blade. As previously mentioned, the discs 26 and 28 are freely seated in the recess 20 so that they can rotate and can slide laterally to a certain extent, and in any case to an extent that they can be separated from tangential contact so that a space will exist between their peripheries. These relationships are shown in the drawing. Thus, in the specific illustrative embodiment referred to above, the discs 26 and 28 have a thickness which is slightly less than the depth of the recess 20, viz. slightly less than A; in., and a diameter of in. The recess 20 then has a horizontal dimension as seen in FIG. 5 of about 1% in. and a vertical dimension just slightly greater than /8 in., with the curvature of the end walls 22 and 24 being such that they closely surround the peripheral portions of the discs without, however, preventing their rotation.

As previously indicated, in accordance with the invention, the discs 26 and 28 are resiliently held in tangential contact, as seen in FIGS. 4 and 5, in such manner that they ca be forced apart by pressing a blade between them. For this purpose, the unit 10 is formed with a tapped hole 44 at one end which extends from the end face 46 of the unit to recess 20. This hole 44 may be formed in the body portion alone or partly in the body portion and partly in the cover plate. Seated in the tapped hole 44 is a spring 48, positioned to act upon the peripheral edge of disc 28, and threadedly engaged in the hole is a screw 50 which can be used to vary the tension of the spring. In the embodiment illustrated, the screw 50 is a set screw which can be suitably adjusted by means of a screw driver, but it can also have any other convenient form, e.g., it can be in the form of a machine screw with a square or hexagonal head to permit direct manual adjustment. The holder 12 is suitably cut away, as indicated at 52, to provide access to the screw. As illustrated, a ball bearing 54 or the like is advantageously interposed between the edge of disc 28 and the spring 48, to facilitate contact, but the ball bearing can be eliminated if desired.

To sharpen a knife, it is merely necessary to draw the a blade through the cutouts in the unit into contact with the adjacent peripheral surfaces of the two cutting discs, as shown in FIG. 1. Thus, the knife is held in a horizontal position, and very little downward force is required. After drawing once between the discs, the sharpening can be finished by two or three light strokes between the discs. For the ordinary sharpening operation with a conventional carving knife, for example, the blade is drawn acrossthe discs in the position illustrated, i.e., without spreading them apart. When, however, an elongated thin (hollow ground) edge is desired, then the blade is pressed down so that the discs separate. It will be seen that the nature of the edge applied can be varied at will, depending upon the type of knife being sharpened, and that the sharpener of the invention automatically accommodates itself to these different requirements.

It will, of course, be understood that various changes and modifications, in addition those already mentioned, can be made in the specific embodiment illustrated without departing from the scope of the invention as defined in the appended claims. For example, the notch or cutout for reception of the knife can have other forms, or can be less deep, the recess in the holder can be shallower so that the sharpening unit does not extend so far into the holder, and the like. In addition, the body portion 14 of the unit can be formed from two separate halves, one having the recess 20 cut out of it and the other having essentially the form of the cover 16, these two halves and the cover plate all being secured together by the screws 18. It is intended, therefore, that all matter contained in the foregoing description and in the drawing shall be interpreted as illustrative only and not as limitative of the invention.

I claim:

1. A knife sharpener comprising, in combination, a housing formed with an internal recess and a cutout communicating with said recess, a pair of metal-cutting discs freely disposed in said recess in co-planar tangential relationship in said housing, but movable in their common plane out of tangential contact, and spring means acting upon one of the discs to urge it into tangential contact with the other disc.

2. A knife sharpener comprising, in combination, a housing formed with an internal recess and means communicating with said recess providing access thereto, a pair of metal-cutting discs freely disposed in said recess in c0-planar tangential relationship in said housing, but movable in their common plane out of tangential contact, and adjustable spring means acting upon one of the discs to urge it under variable pressure into tangential contact with the other disc.

3. A knife sharpener comprising, in combination, a housing formed with an internal recess and means communicating with said recess providing access thereto, a pair of metal-cutting discs freely disposed in said recess in co-planar tangential relationship in said housing with the plane of tangential contact extending through said means to provide access to said discs along said plane of tangential contact, said discs being movable laterally in their common plane, and adjustable spring means acting upon one of the discs to urge it under variable pressure into tangential contact with the other disc.

References Cited by the Examiner UNITED STATES PATENTS 1,767,091 6/1930 Millsap 7687 2,338,033 12/1943 Gallo 76-87 2,436,810 3/1948 Jones 7687 2,617,235 11/1952 Lindahl 7687 X GRANVILLE Y. CUSTER, 111., Primary Examiner. 

1. A KNIFE SHARPNER COMPRISING, IN COMBINATION, A HOUSING FORMED WITH AN INTERNAL RECESS AND A CUTOUT COMMUNICATING WITH SAID RECESS, A PAIR OF METAL-CUTTING DISCS FREELY DISPOSED IN SAID RECESS IN CO-PLANAR TANGENTIAL RELATIONSHIP IN SAID HOUSING, BUT MOVABLE IN THEIR COMMON PLANE OUT OF TANGENTIAL CONTACT, AND SPRING MEANS ACTING UPON ONE OF THE DISC TO URGE IT INTO TANGENTIAL CONTACT WITH THE OTHER DISC. 